Monday
Monday: Define the Problem
Rocket drops a tennis ball onto the patio at the Field. It bounces up past his knee and rolls away under a chair.
Then he rolls the toy car down the cardboard ramp. It shoots off the end and smacks into the wall.
"Hard stops everywhere," he says. "I want a landing pad that catches them gently."
Raven opens the Field Log to a clean page. "What do you notice? You said gently. How gentle? Measured how?"
Nova hovers over the blank page. "Engineers write that down before they build anything," she says.
"Low bounce. Short roll. Made from stuff we already have," Rocket says, counting on his fingers.
Raven writes two headings: what success looks like, and what we are not allowed to change. "Now we are engineering."
The design problem
Your challenge this week: protect a dropped ball or a rolling toy car from a hard stop. You design and build a landing pad.
The engineering standards say it plainly. The more precisely criteria and constraints are defined, the more likely the solution will succeed.
Criteria describe success. Constraints describe limits. Writing both down first is the whole of today's job.
Criteria: what success looks like
A criterion must be something you can measure at the Field. Here are the two this course uses, plus one you add yourself.
Bounce height: when the ball is dropped from a fixed height onto the pad, how high does it come back up?
Stop distance: when the toy car rolls off the ramp onto the pad, how far does it travel before it stops?
Your own criterion might be: the ball stays on the pad, or the pad survives ten drops without falling apart.
Constraints: the limits
Constraints come from the materials, the space, the time and the safety rules. The standards say constraints include scientific knowledge that limits solutions.
Materials: only things your family already has, such as cardboard, paper, rolled socks, a towel, a small cushion and tape.
Size: no larger than a tray or box lid. Time: built in one session. Safety: drops only from standing reach, and soft objects only.
Science: a pad cannot stop the floor from pushing back. The third law says the pad pushes the ball exactly as hard as the ball pushes the pad.
| Kind | Example for the landing pad | How you check it |
|---|---|---|
| Criterion | bounce height below a set mark | measure the bounce with a tape measure |
| Criterion | short stop distance for the toy car | measure from the ramp end to where the car stops |
| Constraint | only materials the family already has | list them before building |
| Constraint | no bigger than a tray | measure the pad |
| Constraint | drops from standing reach, soft objects only | follow the safety callout |
- Read the question.
- Tap your answer.
Why a soft stop is gentler
The forces in a collision come in pairs, and the pair is always equal. So what can a pad change? The time.
A physics text explains that the effect of a force depends on how long it acts, not only on its size.
Padding lets the force that stops an object act over a much longer time. The same stop, spread over more time, needs a smaller force.
That is why a car has a padded dashboard and air bags. It is why you bend your knees when you land from a jump.
| Statement | True or false? |
|---|---|
| Criteria describe what success looks like and can be measured. | ? |
| Constraints are the limits a design must stay inside. | ? |
| A landing pad makes the ball push the pad harder than the pad pushes the ball. | ? |
| Spreading a stop over a longer time makes the force smaller. | ? |
Drops happen only from standing reach, never from a chair or step. The toy car rolls down a book or cardboard ramp on the floor.
The engineering steps follow the Next Generation Science Standards. The force facts come from NASA Glenn and a college physics text at libretexts.org.
Precise work. Tomorrow you plan a fair test so your results will mean something.